The invention relates to a method for purifying a carbon-containing absorption medium that has been spent in a flue gas scrubbing process and which has been removed from a flue gas treatment reactor wherein the removed adsorption medium is subjected to a desorption process in a separate thermal regeneration/desorption apparatus for separating and decomposing pollutants and wherein the pollutant-rich desorption gas is subjected to a further treatment. Furthermore, the invention relates to an arrangement for performing this method.
With the increasing number of flue gas scrubbing devices, with respect to number and capacity the amount of adsorption medium used within such scrubbing devices has also steadily increased, these adsorption media being partially heavily loaded with pollutants. A combustion of the carbon-containing adsorption medium is not feasible or feasible only with a considerable expenditure whereby it has not been possible to date to dispose of especially heavy metals and dioxin in a suitable manner.
From U.S. Pat. No. 4,500,501 a method is known in which the separation of SO.sub.2 and NO.sub.x by catalytic adsorption is performed in two serially connected moving bed reactors. The carbon-containing adsorption medium removed from the second moving bed reactor in line is regenerated in a regenerator arranged downstream, partially replaced and turned into the first flue gas treatment reactor. With this known process it is possible to reactivate the adsorption medium; on the other hand, the contents of toxic substances, especially dioxin, furane, and heavy metals, especially mercury, within the recycled adsorption medium can increase.
Under the given circumstances the pollutant-rich adsorption medium spent during flue gas scrubbing often must be disposed of at special hazardous waste depositories at a respective cost expenditure.
From German published document 3 426 059 a desorption method for carbon-containing adsorption media is known in which temperatures of more than 1000.degree. C. are deemed necessary. In the described method there is further the danger of introducing oxygen into the desorption apparatus.
It is therefore an object of the invention to dispose of heavily polluted carbon-containing adsorption media spend during flue gas scrubbing at comparatively low costs and in an environmentally safe manner.